Simple Use Case

The simple use case includes three OGC Web services: a Sensor Observation Service (SOS), a Web Feature Service (WFS), and a Web Processing Service (WPS). Figure 1 depicts the service composition created for the simple use case.

Figure 1

The SOS used in the ENVISION use case is provided by BRGM via the following endpoint: http://sosades.brgm.fr/. It retrieves groundwater level observations (Observations and Measurements) using sensors which provide piezometer measurements.

The WFS of the Simple Use Case provides information about land use. It returns CORING land cover data of urban fabrics for France. The FeatureTypes represent the classes defined by the Coordinated Information on the European Environment (CORINE) land cover project. The Classification provides 44 land cover classes divided up into 5 main levels. For the use case we look at "Artificial surfaces" especially "Continious urban fabric" and "Discontinous urban fabric" areas. Areas with continious urban fabric are areas with a development structure. The main part of the is covered by buildings, streets and artificial canopy. Areas with discontinous urban fabric are also areas with a development structure. But next to the buildings, streets and areas with artificial canopy, areas with open space occur in significant quantities. The output of this service is encoded as a feature collection.

The WPS for the Envision Simple Use Case implements a process called DroughtClassifiedAlgorithm that calculates which areas are in potential risk of drought in France. It is available at http://giv-wfs.uni-muenster.de:8080/52n-wps-webapp-2.0-RC6-SNAPSHOT/. The underlying idea is based on setting a threshold for groundwater level, considering that levels below this threshold indicate risk of drought, and find out which areas present such a risk. The service takes as input a feature collection from a Web Feature Service, and an observation collection (encoded as O&M) from a SOS provided by BRGM. The feature collection includes CORINE (Coordinated Information on the European Environment) Land Cover data, and two possible feature types are valid:

  • corine:clc00_c111 - Continuous urban fabric
  • corine:clc00_c112 - Discontinuous urban fabric

The observation collection lists piezometer measurements of groundwater level. Each value is timestamped and points to a geolocated feature of interest, in our case the measuring station installed at the corresponding groundwater body. The DroughtClassifierAlgorithm analyses all the values in the observation collection and, for those values below the defined threshold of 2 meters, it performs a spatial match in to retrieve just the features affected from the feature collection. This algorithm is a toy example for the Simple Use Case and aims to simulate an environmental model to predict droughts.